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Profiling of polar metabolites in fruits of Opuntia stricta var. dillenii by ion-pair high-performance countercurrent chromatography and off-line electrospray mass-spectrometry injection

Thi Tran, Thu Minh, Nguyen Thanh, Binh, Moussa-Ayoub, Tamer E., Rohn, Sascha, Jerz, Gerold
Journal of chromatography 2019 v.1601 pp. 274-287
Opuntia stricta var. dillenii, acetonitrile, betalains, butanol, countercurrent chromatography, electrospray ionization mass spectrometry, fractionation, fruits, metabolites, metabolome, molecular weight, monitoring, solvents, tandem mass spectrometry
Electrospray mass spectrometry-profiling guided the metabolome investigation of a C18 reversed phase adsorbate of Opuntia stricta var. dillenii fruits following analytical, and semi-preparative high-performance countercurrent chromatography (HPCCC) fractionation, and visualization of molecular weight elution profiles based on selected single ion-traces.Experimental partition-ratio values KD, and peak widths for detected metabolites were determined. Structural characterization of metabolites, and co-elution effects were monitored in the scan range m/z 150-2200. The polar ion-pair activated solvent system tert.-butylmethylether - n-butanol - acetonitrile - water (0.7% trifluoroacetic acid) [2:2:1:5]) was used for partition-ratio KD improvement of ionic betalains. HPCCC operations were in the head-to-tail mode using the elution-extrusion approach. Selected ESI-MS ion traces visualized the elution of fourty-three metabolites, whereas twenty-one were identified as known betalain pigments, and their classic degradation products, and chlorinated betacyanin artefacts. Potentially, novel fruit metabolites of Opuntia were recognized by unknown molecular weights, and MS/MS fragmentations.Off-line ESI-MS fraction monitoring determined peak elution windows, and resulted in KD-based chromatographic scales. Detectable metabolites were compared by separation- α, and resolution-factors RS revealing a better performance of the analytical HPCCC experiment.Experimental metabolite KD-values from analytical and semi-preparative HPCCC runs were widely consistent, and confirmed the reproducibility of the technique based on the used sample material.